THE Chinese New Year celebrations may be a little less colourful in Beijing this weekend. In the wake of the worst smog China鈥檚 capital has ever seen, residents have been asked to .
The city is known for its caustic air, but even by its own standards, the past month has been a killer. City dwellers were advised to stay indoors because air pollution was off the charts. 鈥淚 tried to avoid going out unnecessarily and opening windows,鈥� says resident ..Yu Sun. Hospital admissions for respiratory problems and traffic accidents were up as people struggled to go about their lives in drastically reduced visibility. Levels of tiny particles less than 2.5 micrometres across, known as PM2.5, soared to 886 micrograms per cubic metre at 8 pm on 12 January (see 鈥�graph鈥�), according to . This is the highest level on record and meant that the day鈥檚 average reading was 22 times what the .
The extreme smog is a symptom of an ongoing problem. Rampant growth, coupled with east China鈥檚 geography, leaves the entire region in the grip of dangerous smog every winter. Mountains to the north and west hem in pollution and there is little wind in winter. In recent weeks warm air sitting on top of the cold ground-level air has also kept a lid on the smog.
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Pollution comes from various sources. Coal-fired power stations, factories and refineries, road vehicles, and coal-fired domestic heating all play their part. Worse, this winter has been exceptionally cold, so the country has been burning more coal than usual.
China has been trying to address the problem, banning the most polluting vehicles and fitting sulphur dioxide scrubbers to coal-fired power plants. As a result, Beijing鈥檚 levels of but levels of nitrogen oxides and particulates remain high, plus ground-level ozone levels have risen since 2001.
It鈥檚 not just an issue for China. Once the stagnant air starts moving in spring, 鈥渋t鈥檚 not unusual to see smog from eastern China transported across Korea and Japan鈥�, says David Cohen from the Australian Nuclear Science and Technology Organisation. East Asian ozone is even found on the West Coast of the US, carried by the jet stream, says Owen Cooper of the National Oceanic and Atmospheric Administration in Boulder, Colorado. This only amounts to about 10 per cent of US ozone, but it makes a difference. Without the import, .
Gasping for breath
The obvious comparison is with the London smog of 1952 that killed 4000 in a single week. In December 1952, concentrations of PM2.5 reached 3000 micrograms per cubic metre in London. Levels in Beijing are far lower and no deaths have been reported so far. But, the London toll suggests that people are likely to become ill and die in the coming weeks in Beijing, despite PM2.5 levels easing to 241 micrograms per cubic metre by 31 January. 鈥淸Deaths] will certainly increase during this episode,鈥� says Tony Fletcher of the London School of Hygiene and Tropical Medicine. Most are likely to die from .
No one is sure exactly why these particles are so destructive, but clues exist. A 2008 study showed that tiny particles damage the 鈥済ood cholesterol鈥� that prevents plaques forming inside blood vessels. These deposits cause blockages that trigger strokes and heart attacks, and life-threatening blood clots in the lungs.
Air pollution is the fourth highest avoidable risk factor for death in east Asia, behind high blood pressure, not eating enough fruit and smoking. In 2010, pollution , two-thirds of the global total, according to Stephen Lim of the Institute for 午夜福利1000集合 Metrics and Evaluation in Seattle, Washington.
Exposure to airborne pollutants can even affect future generations: it is linked to premature deliveries and . There is also evidence that children breathing polluted air can develop smaller lungs, making them more prone to ill health.
In search of blue skies
The US and Europe have slashed air pollution over the last few decades, by moving their polluting industries to Asia, but regulations and clean technologies have played a role. Similar approaches could reduce pollution in east Asia 鈥� .
In response to the smog, China has shut down factories and restricted vehicle use. 鈥淚t does help,鈥� says Cooper, 鈥渂ut by the time things get where they are, it doesn鈥檛 help much.鈥�
The government adopted a similar approach before the 2008 Beijing Olympics. Factories were shut and traffic limited. Satellites registered a .
This had an immediate beneficial effect, though it didn鈥檛 last. In Beijing 125 young citizens participated in a study of substances in blood that raise the risk of heart disease if elevated. Their concentrations , as pollution rose. 鈥淭he public and the Chinese government should be reminded about this legacy of the Olympics,鈥� says Jim Zhang of the University of Southern California. 鈥淎chieving short-term economic profits by using dirty fossil fuels will make society pay a high price.鈥�
鈥淪ociety will pay a high price for economic profits made using dirty fossil fuels鈥�
Turning things off isn鈥檛 sustainable in the long term. By October 2009, 60 per cent of the . Only systemic changes can stop the emissions permanently. Some changes, like cuts in sulphur dioxide, are under way. Cooper says a switch from coal-based home heating to electric would also help.
But some forms of pollution are harder to curtail. Power plants will need a wholesale redesign to cut their nitrogen oxide emissions. And while China is insisting that new cars meet European emissions standards, the number of cars is skyrocketing because of the growing middle class.
It鈥檚 an uphill struggle but Hong Kong has set an encouraging example. In 1990, the country restricted the sulphur content of vehicle fuel to 0.5 per cent by weight. One year later, average concentrations of sulphur dioxide had tumbled by 80 per cent in the most polluted districts 鈥� .
China will struggle with the sheer scale of its industry. Poor enforcement of the pollution regulations at the provincial level, and a lack of studies that track pollution to its source, exacerbate the problem. 鈥淓ven with pollution controls, they鈥檙e going to have air quality issues for years to come,鈥� says Cooper. He adds that even if pollution levels were halved, the recent smog would still have exceeded the safe level many times.
In the last week, . 鈥淭oday is a valuable day 鈥� the sky is blue and there is no smog,鈥� says journalist and Beijing resident Jiao Li. But there is little doubt it will return.
